The present invention relates to a novel steroidal ketone compound which can be used for an device in optical parametric oscillation, higher harmonic wave generation, electro-optical switching, etc., a process for producing the same, a non-linear optical material and a non-linear optical device.
Non-linear optical materials which are expected to play an important role in the optical communication technology and the like exhibit such functions as optical mixing, optical parametric oscillation, higher harmonic wave generation, electro-optical switching, optical rectification and light-light switching, based on the non-linear optical susceptibility of the materials. Previously, inorganic crystals such as those of KH.sub.2 PO.sub.4 and NH.sub.4 H.sub.2 PO.sub.4 have been used as such materials. However, these materials are disadvantageous in that their nonlinear optical susceptibility is considerably low for practical use and further they are deliquescent.
Organic non-linear optical materials, which make use of the polarization of the .pi. electron system, have a high non-linear optical susceptibility as compared with prior materials, and also are excellent in high-speed response and damage threshold value, so that research and development thereof have been widely forwarded recently in various fields. Recent results of such efforts are described in detail in, for example, "Nonlinear Optical Properties of Organic and Polymeric Materials" (edited by D. J. Williams, ACS Symposium Series No. 233, published by American Chemical Society, Washington, D.C., 1983), "Nonlinear Optical Properties of Organic Molecules and Crystals", Vol. 1 and Vol. 2 (edited by D. S. Chemla and J. Zyss, published by Academic Press, Orlando, Fla., 1987), "Nonlinear Optical and Electroactive Polymers" (edited by P. N. Prasad and D. R. Vlrich, published by Prenum Press, New York, 1987) and "Nonlinear Optical Effects in Organic Polymers" (edited by J. Messier, F. Kajar, P. N. Prasad and D. R. Vlrich, published by Klewer Academic Publishers, Dordrecht, The Netherlands, 1989).
However, no material has yet been found which has a large non-linear optical coefficient of such an extent as enables satisfactory attainment of the purpose in low output lasers as semiconductor lasers. Also, the problem of poor thermal stability, which in a shortcoming common to organic materials, has not been solved. Accordingly, further development of novel materials is eagerly desired.